More than 200 musicians from four major Allentown bands will join forces next Sunday afternoon for the 1985 Festival of Bands in Muhlenberg College Memorial Hall.

The 3 p.m. concert will present the combined efforts of the Municipal Band of Allentown, the Marine Band of Allentown, the Pioneer Band of Allentown and the Allentown Band. In addition, special guest performers this year will be the recently reorganized Lehigh Valley Junior Band, formerly the Allentown Juvenile Band.

There will be no admission charge for the festival, but a collection for donations will be taken during intermission for the 33rd annual benefit for the Lehigh Valley Association for Retarded Citizens (LARC).

With a combination of funds from the concert collection, patron listings and the sale of program advertisements, officials hope to top the $5,000 raised for LARC at last year's event.

According to Mrs. Edward B. Rentschler, program coordinator and executive secretary of Allentown Music Festivals, Inc., the organization has contributed nearly $150,000 to LARC since it began sponsoring the event some 30 years ago.

Approximately 4,500, a near-capacity crowd, attended last year's performance. Organizers recommend that those planning to attend next Sunday's event arrive before 2:30 p.m. There will be no reserved seating, and the fire marshal will close the hall when it has reached capacity.

The massed bands will open the festival with "Sinfonians," "Orpheus Overture" and "Washington Grays," under the direction of Raymond Becker, Marine Band conductor.

Jay Durner, conductor of the Pioneer Band, will lead the assembled group in the finale of the "New World" symphony and Fillmore's "Klaxon."

Under the direction of Ronald Demkee, Allentown Band conductor, the bands will perform "Young Americans," a selection from Gershwin's "Porgy and Bess" and Sousa's "Hail to the Spirit of Liberty."

During the final segment of the program, Richard Hinkle, Municipal Band conductor, will direct the massed band in "Chorale and Shaker Dance" and, with the Junior Band joining in, "God of Our Fathers" and the "Stars and Stripes Forever."

"We are trying to get more young people interested in band music, and we think the Junior Band is one of the ways this can be done," said Wilfred M. Post Jr., a member of the executive board of Allentown Music Festivals, Inc.

The group of young musicians numbers approximately 45, and their ages range from 11 to 18. They perform 12 to 15 concerts each summer season, as well as an annual Christmas concert.

"We are pleased that we were asked to perform in the festival this year," said James J. D'Annibale, Junior Band director. "It will be a unique experience for the kids. They are looking forward to it. And, we hope the exposure may inspire more children to join."

D'Annibale said the band has openings for all instruments and encourages interested young musicians to audition.

Doors will open at 2 p.m. The section of preferential seating for patrons and advertisers will be opened to the general public after 2:45 p.m.